Perpetual Sand is a common enemy on floors 202-213 of Tartarus's Harabah Block. They will be the subject of one of Elizabeth's Requests starting December 4th and will drop Sand of Time while the quest is active. Returning to Elizabeth with 3 Sand of Time items will complete the quest.
Perpetual Sand is a common enemy on Paradise 1 of Heaven. It will attempt to use Old One on the party before attacking. It may drop Golden Sand after being defeated. Selling 6 Golden Sand will unlock the Mythos Robe female armor in the shop.
In Golden, it appears in Paradise 1 to 4. It may also drop Rose Quartz for trade at Shiroku Pub.